At present, with the development of communication technology, electronic equipments such as mobile phones, tablet PC (tablet personal computer) and the like are widely used, and a touch screen is one of important components of these electronic equipments. Surface of a touch screen generally has a substrate for protecting internal structure of the screen, wherein it is usually necessary to provide printing layers within the substrate to seal mechanical structures. When the printing layers have larger width, light leakage may occur on the touch screen. A user can see clear printing lines from the front of the screen, which affect display effect.